Pulverized-fuel furnace



Apr. 24, 1923.

H. G. BARNHURST PULvERzED FUEL FUHNACE Filed Febv 17,

1919 3 Sheets-Sheet l .I @Wrme-EE@ l... m. Q Q N /M ./A/l a WI.: -Wb uMmmm: $5 I im HHH Hmmmm HW m I llrllllm'l. ...F HHHHMWJMW HHHMWW n HWin. 'JI s Auld! wm|%\z .N n/ www? .In

Apr. 24, 1923. 1,452,952

- H. G. BARNHURST 1 PULVERIZED FUEL FURNACE Filed Feb. 17, 1919 sshefets-sheet 2 INVENTOR @am W4 ATToR* Yf,

mmf, 24, w23. mm@

Y H. G. BARNHURST PULVERZED FUEL FURNACE Filed Feb. 17 1919 3Sheets-Sheet 3 FFH f.

. T g Q D &\ ,f p

INVENTOR ATTORNEYJ Patented Appr. 24, 1923.

UNITEID STATES PATENT OFFICE.

HENRY G. BARNHURST, OF ALLENTGWN, PENNSYLVANIA, ASSIGNOR TO FULLEB-ENGINEERING COMPANY, A CORPORATION F PENNSYLVANIA.

rULvEmzE'n-FUEL summon. l

Application led February 17, 1919. Serial 170.277,411.

To all whom t may concern.'

Be it known that I, HENRY G. BAnN- HURST, a citizen of the UnitedStates, residing at 1441 Hamilton Street, Allentown, 1n

5 the county of Lehigh, State of Pennsylvania, have invented certain newand useful Improvements in Pulverized-Fuel Furnaces; and I do herebydeclare the following to be a full, clear, and exact descrlption of theinvention, such as will enable others skilled inthe art to which itappertalns to make and use the same. y

This invention relates to furnaces adapted for the utilization ofpulverized coal. In

l5 such furnaces it is necessary, in order that pulverized fuel may beburned with any degree of success, that the cross sectional area of thecombustion chamber transverse to the direction of travel of the roductsof combustion be large in proportion to theair and fuel admittedso thatthe velocity of flow of the gases will be below that which will produceerosion of the refractory lining of the walls of the furnace. Failure torecognize combustion chamber with reference to the velocity of travel ofthe hot gases through the furnace has been the principal reason for thelack of success of attempts to burn pulver,- ized fuel in furnacesoriginally designed and built for the combustion oflump fuel. In suchbases, the high temperature existing within the furnace duringcombustionof pulverized fuel reduces the refractory llining to a more orless plastic condition, and in this condition, thehigh velocity of thefurnace gases results in erosion which soon amounts to destruction'. Aconsiderable increase in the volume of the combustion chamber isrequired, therefore, in order that any substantial degree of successinthe burning of pulverized fuel may be attained.V In many cases, suchan increase of volume 1s obtained by remodelling the combustion chambersof existing furnaces.

While the amount of solid residue resulting from the combustion ofpulverized fuel is considera-bly less than in the case of lump fuel, intime it amounts to a substantial deposit, partioularly at the bottom ofthe combustion chamber of a furnace. The portions the necessity forproperly proportoning the n of such a deposit lying upon or immediatelyadjacent the fioor of the combustion chamber, where heat is most rapidlyabsorbed, are generally in the form of fine sand, but in the upperportions of the mass the residue assumes the form of slag under theinfluence of the high temperature existing in the combustion chamber.Any considerable accumulation of residue results in a correspondlngdecrease in the space in the combustion chamber available for theburning gases. Since the proper proportioning of the combustion chamberis of particular importance. for reasons explained above, anysubstantial alterations in its dimensions result in l a marked decreasein the efficiency of the furnace, and particularly is this the casewhere existing furnaces have been remodelled for the purpose of burningpulverized fuel, as in such cases there is usually littleor no excessvolume of'the combustion chamber over the minimum amount required forefficient combustiomfand anydecrease in the volume materially cuts downthe efiiciency. n v

In order to prevent the accumulation of residue, it is the practice toremove the same from time totime, but this requires manual labor,necessitates the'insertion of suitable tools withinl the combustionchamber and, Vif not frequently performed, will not keep down theaccumulation of material sufficiently to prevent detrimental effectsupon the efficiency of combustionas well as upon the furnace structure,due to erosion and other causes. A

It is jan object of this invention to obviate the disadvantagesmentioned above by providing a furnace having a relatively largecombustion chamber into which a mixture of pulverized fuel and air maybe fed and which is provided with means for removing thesolid residuesof combustion as they are produced, so that accumulation thereof will eprevented and the entire space within the combustion chamber will beavailable at all times for theburning ofthe fuel. 'The possibilityofvariations in efficiency due to changes involume of the space occupiedby the burning fuel is, therefore,l eliminated, and since the residuesare continually removed, they are discharged in sand-like condition,rather than in the form of relatively large masses of slag.

he particular nature of the invention, as well as other advantagesthereof, will appear more clearly from a description of a preferredembodiment, and for this purpose the furnace has been illustrated inconnection with a water tube boiler. In the accompanying` drawings,

ig. 1 is a plan view of the appara-tus for removing the residues ofcombustion, the walls of the furnace being shown in section; Fig. 2 isan elevation in section along the line 2 2 of Fig. 1 Fig. 3 is atransverse section along the line 3 3 of Fig. 1; Fig. 4 is an enlargedsectional view through the sprocket chains and the elements carriedthereon; Fig. 5 is a plan View of a portion of the chains and otherelements; Fig. 6 is a det-ail view in section along the line 6 6 of Fig.4; and Fig. 7 is a sectional elevation of the combustion chamber portionof the complete furnace, the movable hearth being shown in outline.

Referring to the drawings in which similar reference characters denotesimilar parts throughout the several views, the furnace has a front wall1, rear wall 2 and side wallsy 3 forming a combustion chamber 4 ofrelatively large volume and otherwise designed in accordance with theprinciples applicable to furnacesA in which pulverized fuel is to beburned. The hot gases of combustion flow to the water tubes 5 through apassage at the top of the combustion chamber.

Pulverized fuel is stored i'n a hopper 6 and fed into a tube 7 throughwhich it passes by gravity into a burner nozzle 8 projecting into anopening in the front wall of the furnace. to the nozzle 8 to produce acurrent of air for carrying the pulverized fuel into the furnace.Additional air may be entrained and carried into the furnace through theannular space surrounding the blower tube, the amount of this additionalair being s ubject tothe control of a regulating cone 10 slidablymounted on the blower tube.

The side walls 3 of the furnace are formed with lower inclined portionsl1 which terminate in overhanging portions 12 carriel upon verticalwalls mounted upon a suitable foundation 13 which also constitutes atank or trough adapted to contain liquid for cool- A blower 9 isconnected chamber are sprocket wheels 20, over which pass sprocketchains 21 carrying the heat resisting elements of the hearth.

The construction of the sprocket chains appears most clearly in Figs. 4,5 and 6. Each link of each chain is made up of two parts, an inner link22 and an outer link 23. One end of each of the links is placed out ofalinement with the outer end, so that the links may be fitted togetherto make up a chain, pivot pins 24 of any suitable form being used forconnecting the links to each other. Both the. inner and outer links ofeach pair are provided with circular apertures in alinement with eachother, and adapted to receive the cylindrical end 25 of a transverse rodhaving a rectangular cross section throughout the portion lying betweenthe inner links. The transverse rods are adapted to be held in place bynuts 27 screwed upon their ends, and in order to give a flat bearingsurface for the nuts, the outer link 23 of each pair is provided with aboss 28. The inner link 22 of each pair is provided with a pair ofparallel ribs 29 between which the end of the rectangular portion 26 ofthe rod is adapted to vfit to prevent the rod from turning in the links.

The transverse rods serve as supports for the heat resisting elements30. a number of which are mounted vupon the rectangulaiportion of eachrod, correspondingly shaped apertures being provided in the elements forthis purpose. These elements, which may be constructed of cast iron,fire brick or any other suitable heat iesisting material, have atriangular shape, and the portion 31 which is exposed to the combustionchamber during travel through the same, is somewhat. wider than theportion 32 located on the other side of the supporting rod. There isthus formed in effect a series of heat resisting grate bars between thesprocket chains, but since each of these bars is made up of a pluralityof separate elements, any damaged or broken elements may be replacedwithout requiring that the other elements of the same bar be discarded.The, construction thus lends itself to the cheap and convenient renewalof damaged or defective elements.

For the purpose of moving the hea'rth,

the shaft 18 is extended beyondl the bearing 17 at one side of theapparatus and carries a gear 33 which meshes with a worm 34 on a shaft35 leading to a speed reducing mechanism 36 of any suitableconstruction. The driving element of the speed reducing mechanism isconnected by means of a shaft 37 to a motor 38 or other source of power.For the purpose of removing from the hearth the residue brought out ofthe combustion chamber, there is provided a suitable chute 39, the upperend of which lies immediately above the heat resisting elements as theyleave the combustion chamber, but it will be understood that insteadofthe exact arrangement shown any other suitable'device for removingmaterial from the bars of the hearth may be used. At the point 40 wherethe hearth enters the combustion chamber the wall of the latter may bebrought closely adjacent the tops of the heat reslsting bars,`

i to a plate 42 attached to the outer face of the wall of the combustionchamber. As shown most clearly in Fig. 3, the ends of the door areadapted to engage the overhanging portions 12 of theJ wall of thecombustion chamber to prevent the door from swin ing inwardly andallowing air to enter tie c ombustion chamber. The door should be ofsufficiently light construction so that it may be swung outward by anydeposit upon the hearth without scraping off the deposit and causing itto clog up the exit passage.

In the operation of the furnace described above, pulverized fuel is fedinto the burner nozzle 8 and carried into the combustion chamber by theair blast from blower 9. Any additional air that may be required forcomplete combustion ofthe fuel is supplied through the l.spacesurrounding the blower tube. The solid residues resulting fromcombustion of the fuel within the chamber are deposited upon the hearthwhichis driven from the motor 38 under the control of the speed reducingmechanism 36. Over the upper portion of their@ paths, the sprocketchains of the hearth travel along the upper guides 14 to prevent thehearth from sagging while it is moving through the combustion chamber,

and over the lower portion of their paths the sprocket chains travelover the lower guide 15. thus preventing sagging of the chains Whilethey are passing through the tank. The tank is preferably filled with'water or other cooling liquid so that the elements of the hearth whichare heated during *heir passagethrough the-combustion chamber and by thehot residues deposited there- .on are cooled before they again enter thechamber. This preventsoi-'erheating of the parts of the hearth. and isalso conducive to the most efficient removal of the residues. since whendeposited upon a relatively cool surface. they` are in asand-likecondition as distinguished from the slag-like condition assumed by suchresidues when they are deposited upon a relatively hot surface and areyalso subjected to the high temperature existing Within the combustionchamber. The sand-like condition of the residues enables them to bereadily removed from the hearth as they are carried out of thekcombustion chamber.

I claim:

1. A furnace for burning pulverized fuel, comprising the combination ofa relatively large combustion chamber, means for feeding a mixture ofpulverized fuel and air into the combustion chamber, an endless conveyormounted to travel through the bottom of the combustion chamber, shaftsfor supporting the conveyor, means for driving one of the shafts tocause travel of the conveyor to carry residues of combustion depositedthereon out of the combustion chamber, and means at the front and rearof the furnace contacting substantially closely with the conveyor andpreventing a connection betweenl the interior of the furnace and theatmosphere.

2. A furnace for burning pulverized fuel, comprising the combination ofa relatively large combustion chamber, means for feeding a mixture ofpulverized fuel and air into the combustion chamber, an endless conveyormounted to travel through the bottom of the combustion chamber over theupper portion of its path, shafts located outside the combustion chamberand over which the conveyor passes, means for driving one of the shaftsto cause travel of the conveyor to carry residues of combustiondeposited thereon out of the combustion chamber, and a tank beneath thecombustion chamber, adapted to contain cooling liquid to submerge theconveyor while it is travelling over the lower portion of its path.

3. A furnace for burning pulverized fuel. comprising the combination ofa relatively large combustion chamber. means for feeding a mixture ofpulverized fuel and air into the combustion chamber, means for effectingthe continuous removal of the residues of combustion so that they are ina finelyv divided condition when removed, and lan entrance aperture atthe rear of the furnace substantially the size of the outer dimensionsof the means vfor effecting the continuous `removal ofthe residue, andmeans at the front of the furnace adjustable to correspond with thecombined dimensions of the residue and the means for effecting thecontinuous removal thereof.

4. A furnace for burning pulverizedflzl. comprising the combination ofa/relatively large combustion chamber. means for feeding a mixture ofpulverzed fuel and air into the combustion chamber. an endless conveyormounted to travel through the bottom of the combustion chamber over theupper portion of its path, shafts .located outing one of the shafts tocause travel of the conveyor to carry residues of combustion deositedthereon out of the combustion chamr, entrance means for the endless con-5 veyor limited to substantially the outervdimensions thereof, and anadjustable exit means at another portion of the furnace for permittingthe passage therethrough of the mamas endless conveyor and its load, anda tank beneath the combustion chamber adapted to contain cooling liquidto submerge the conveyor While it is travelling'over the lower portionof its path.

ln testimony whereof l affix my signature.

HENRY G. BARNHURST.

